I'm sitting in an interview room in a police station somewhere in central London. A detective from Leicestershire constabulary's serious crime unit is handing me pieces of paper. "Have you ever seen these before?" he asks. "Has anyone ever passed them to you? Have you ever passed them on to anyone else?" The pieces of paper are copies of witness and police statements that formed the basis of the ITV News investigation into the Stockwell shooting of Jean Charles de Menezes. Of course I've seen them before - I was the producer on the story. The detective knows I've seen them before, and he knows that I know that he knows I've seen them before. But, as I have done countless times that day, I reply in a flat monotone "no comment". The detective sighs, reaches for another statement and the process continues.

It is October 5 last year, possibly around 7pm - it's hard to tell without a watch. Earlier, at around 1pm, the police turned up at my house to arrest me. I was involved in an ITV News investigation exposing a series of police blunders leading to the shooting on July 22 2005 - the day after the failed London bombings.

Everyone was shocked when news first broke that a suspected terrorist had been shot on the London underground. Reports claimed he was acting suspiciously and wearing a bulky jacket. The public was led to believe he jumped over the ticket barrier at Stockwell tube station and charged down the escalator in what appeared to be another terrorist act. Witnesses seemed sure of what they'd seen.

Some reports speculated that perhaps plain clothes police had tried to stop him and that the Brazilian had panicked and run away - it later transpired that he had overstayed his visa.

But only a week later it emerged that the truth was far more disturbing. My girlfriend, Louise, was at a barbecue with a friend who worked at the Independent Police Complaints Commission. Knowing that I was a producer for ITV News, the friend, Lana Vandenberghe, told Louise she had some information about what really happened the day Jean Charles was shot.

Under surveillance

It took another two weeks to get the full picture - and when the ITV evening news on August 16 revealed the catastrophic failure of the surveillance operation it caused an absolute storm.

Police statements and witness accounts - all part of an internal IPCC investigation into the shooting - proved that Jean Charles was completely innocent. He had been mistaken for someone else as he left the block of flats under surveillance that morning. He wore a light denim jacket and was walking at a normal pace - he even picked up a Metro newspaper - as he walked into Stockwell station. He used a ticket to get through the barriers and was clearly unaware he was being followed. He had already taken a seat on the train when police officers stormed the carriage, wrestled him to the ground and shot him eight times.

The story quickly travelled around the world and ITV News was inundated with calls from newspapers and TV stations wanting to find out more. It made the front page of almost every British newspaper the next day.

For me personally, working on a story such as this represented everything journalism should be about: righting wrongs, exposing lies, standing up for someone who couldn't speak for himself.

But despite our efforts to protect the source and keep her identity hidden, it quickly gained currency in the media that the leak had come from within the IPCC.

Two days later, Lana was suspended. Within a week, her landlady - a colleague at the IPCC - evicted her.

Things got worse still when the IPCC called the police in to investigate the leak, and in a dawn raid at her new home on September 21, they arrested Lana on suspicion of theft, misconduct in a public office and various other misdemeanours.

My girlfriend Louise was next to be arrested, on October 5, in a second dawn raid by Leicestershire's serious crime unit, and called to warn me that I'd most likely be next. I wasn't really worried about that - I had been expecting it. I was more concerned for Louise - three weeks earlier, on my birthday, we found out that she was pregnant. Given the stress of the arrest and incarceration, I was desperately worried for the health of our baby.

A few hours later, I was taken by police to Bishopsgate Police Station in London. I was put in a cell without any clear idea if anyone knew exactly where I was. On my way in, I noticed a pair of shoes outside the cell next to mine. I recognised them - they belonged to Louise. She had been there for eight hours and I had no way of knowing if she was OK.

Perhaps three hours passed before I saw my lawyer. In fact, he had arrived some two hours earlier, but the police said it "hadn't been convenient" for me to see him then.

A lack of suitable rooms at Bishopsgate meant a drive to another station for my interview. The detectives wanted to establish the link between Lana, Louise and me, but my lawyer advised me not to answer any questions.

The officers were clearly frustrated by this and resorted to a good cop/bad cop routine. One suggested that if I'd done nothing wrong there was no reason not to talk to them, the other warned that I was an accessory to a very serious crime and my silence was making matters worse.

Bug sweeper

It was late by the time I eventually got home. Tired and angry, I opened the front door to discover that my flat had been raided and searched. Laptops, mobile phones, cameras, CD-Roms, even press cuttings from around the time of the De Menezes reports had been taken.

The flat was a complete mess, and only the most cursory effort had been made to put things back. Oddly, a chair from the bedroom had been left in the bathroom. A carbon copy of a warrant was casually left on the fridge.

It was the chair that threw me. What was it doing in the bathroom? It was positioned right under the light fitting and all sorts of questions went through my head.

Had I been bugged? I decided not to take any chances and went to an electronics store the next day to buy a bug sweeper, which I ran over the flat.

I didn't find anything but that did nothing to assuage the feelings of paranoia, especially after being warned that my landline could well be tapped and any email accounts almost certainly raided. I even found myself checking out a white van that had been parked for days across the road from my flat.

Over the next eight months, Louise, Lana and I would answer bail a further four times. Each time, police could see Louise's baby bump getting bigger, but this did not deter them from locking her up in a cell, sometimes for several hours. Once they offered her a blanket infested with lice. Another time, they offered her no food or drink for over five hours, despite the canteen being just minutes away.

Interviews made it clear the police had delved into our bank accounts and credit records. Text messages retrieved from our phones were read out to us. Silly everyday emails about money, or the lack of it, were twisted and interpreted as a financial motive for the alleged crime.

The police were thorough, I'll give them that - but they just could not seem to countenance the idea that the only motivation was a desire on the part of our IPCC source to get the truth out. The only solace was that we hadn't been arrested under the Terrorism Act. One day in a police cell is bad enough, 28 days must be a nightmare.

The investigation was dropped this month. At the time of writing, no charges have been brought against any of the officers involved directly or indirectly in the shooting.

Jean Charles was innocent. But since his death he has been presented as a terrorist, an illegal immigrant, even a rapist. That this last allegation was completely untrue barely warranted a mention in most of the mainstream media. It's quite conceivable no one will ever be held to account for his death. But his family want, and are entitled to, justice. If I had to, I would do all this again. I would want someone to do the same for my child.